// SPDX-License-Identifier: GPL-2.0
/*
 * IBM/3270 Driver - console view.
 *
 * Author(s):
 *   Original 3270 Code for 2.4 written by Richard Hitt (UTS Global)
 *   Rewritten for 2.5 by Martin Schwidefsky <schwidefsky@de.ibm.com>
 *     Copyright IBM Corp. 2003, 2009
 */

#include <linux/module.h>
#include <linux/console.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/panic_notifier.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/reboot.h>

#include <asm/ccwdev.h>
#include <asm/cio.h>
#include <asm/cpcmd.h>
#include <asm/ebcdic.h>

#include "raw3270.h"
#include "tty3270.h"
#include "ctrlchar.h"

#define CON3270_OUTPUT_BUFFER_SIZE 1024
#define CON3270_STRING_PAGES 4

static struct raw3270_fn con3270_fn;

static bool auto_update = true;
module_param(auto_update, bool, 0);

/*
 * Main 3270 console view data structure.
 */
struct con3270 {
        struct raw3270_view view;
        struct list_head freemem;       /* list of free memory for strings. */

        /* Output stuff. */
        struct list_head lines;         /* list of lines. */
        struct list_head update;        /* list of lines to update. */
        int line_nr;                    /* line number for next update. */
        int nr_lines;                   /* # lines in list. */
        int nr_up;                      /* # lines up in history. */
        unsigned long update_flags;     /* Update indication bits. */
        struct string *cline;           /* current output line. */
        struct string *status;          /* last line of display. */
        struct raw3270_request *write;  /* single write request. */
        struct timer_list timer;

        /* Input stuff. */
        struct string *input;           /* input string for read request. */
        struct raw3270_request *read;   /* single read request. */
        struct raw3270_request *kreset; /* single keyboard reset request. */
        struct tasklet_struct readlet;  /* tasklet to issue read request. */
};

static struct con3270 *condev;

/* con3270->update_flags. See con3270_update for details. */
#define CON_UPDATE_ERASE        1       /* Use EWRITEA instead of WRITE. */
#define CON_UPDATE_LIST         2       /* Update lines in tty3270->update. */
#define CON_UPDATE_STATUS       4       /* Update status line. */
#define CON_UPDATE_ALL          8       /* Recreate screen. */

static void con3270_update(struct timer_list *);

/*
 * Setup timeout for a device. On timeout trigger an update.
 */
static void con3270_set_timer(struct con3270 *cp, int expires)
{
        if (expires == 0)
                del_timer(&cp->timer);
        else
                mod_timer(&cp->timer, jiffies + expires);
}

/*
 * The status line is the last line of the screen. It shows the string
 * "console view" in the lower left corner and "Running"/"More..."/"Holding"
 * in the lower right corner of the screen.
 */
static void
con3270_update_status(struct con3270 *cp)
{
        char *str;

        str = (cp->nr_up != 0) ? "History" : "Running";
        memcpy(cp->status->string + 24, str, 7);
        codepage_convert(cp->view.ascebc, cp->status->string + 24, 7);
        cp->update_flags |= CON_UPDATE_STATUS;
}

static void
con3270_create_status(struct con3270 *cp)
{
        static const unsigned char blueprint[] =
                { TO_SBA, 0, 0, TO_SF,TF_LOG,TO_SA,TAT_COLOR, TAC_GREEN,
                  'c','o','n','s','o','l','e',' ','v','i','e','w',
                  TO_RA,0,0,0,'R','u','n','n','i','n','g',TO_SF,TF_LOG };

        cp->status = alloc_string(&cp->freemem, sizeof(blueprint));
        /* Copy blueprint to status line */
        memcpy(cp->status->string, blueprint, sizeof(blueprint));
        /* Set TO_RA addresses. */
        raw3270_buffer_address(cp->view.dev, cp->status->string + 1,
                               cp->view.cols * (cp->view.rows - 1));
        raw3270_buffer_address(cp->view.dev, cp->status->string + 21,
                               cp->view.cols * cp->view.rows - 8);
        /* Convert strings to ebcdic. */
        codepage_convert(cp->view.ascebc, cp->status->string + 8, 12);
        codepage_convert(cp->view.ascebc, cp->status->string + 24, 7);
}

/*
 * Set output offsets to 3270 datastream fragment of a console string.
 */
static void
con3270_update_string(struct con3270 *cp, struct string *s, int nr)
{
        if (s->len < 4) {
                /* This indicates a bug, but printing a warning would
                 * cause a deadlock. */
                return;
        }
        if (s->string[s->len - 4] != TO_RA)
                return;
        raw3270_buffer_address(cp->view.dev, s->string + s->len - 3,
                               cp->view.cols * (nr + 1));
}

/*
 * Rebuild update list to print all lines.
 */
static void
con3270_rebuild_update(struct con3270 *cp)
{
        struct string *s, *n;
        int nr;

        /* 
         * Throw away update list and create a new one,
         * containing all lines that will fit on the screen.
         */
        list_for_each_entry_safe(s, n, &cp->update, update)
                list_del_init(&s->update);
        nr = cp->view.rows - 2 + cp->nr_up;
        list_for_each_entry_reverse(s, &cp->lines, list) {
                if (nr < cp->view.rows - 1)
                        list_add(&s->update, &cp->update);
                if (--nr < 0)
                        break;
        }
        cp->line_nr = 0;
        cp->update_flags |= CON_UPDATE_LIST;
}

/*
 * Alloc string for size bytes. Free strings from history if necessary.
 */
static struct string *
con3270_alloc_string(struct con3270 *cp, size_t size)
{
        struct string *s, *n;

        s = alloc_string(&cp->freemem, size);
        if (s)
                return s;
        list_for_each_entry_safe(s, n, &cp->lines, list) {
                list_del(&s->list);
                if (!list_empty(&s->update))
                        list_del(&s->update);
                cp->nr_lines--;
                if (free_string(&cp->freemem, s) >= size)
                        break;
        }
        s = alloc_string(&cp->freemem, size);
        BUG_ON(!s);
        if (cp->nr_up != 0 && cp->nr_up + cp->view.rows > cp->nr_lines) {
                cp->nr_up = cp->nr_lines - cp->view.rows + 1;
                con3270_rebuild_update(cp);
                con3270_update_status(cp);
        }
        return s;
}

/*
 * Write completion callback.
 */
static void
con3270_write_callback(struct raw3270_request *rq, void *data)
{
        raw3270_request_reset(rq);
        xchg(&((struct con3270 *) rq->view)->write, rq);
}

/*
 * Update console display.
 */
static void
con3270_update(struct timer_list *t)
{
        struct con3270 *cp = from_timer(cp, t, timer);
        struct raw3270_request *wrq;
        char wcc, prolog[6];
        unsigned long flags;
        unsigned long updated;
        struct string *s, *n;
        int rc;

        if (!auto_update && !raw3270_view_active(&cp->view))
                return;
        if (cp->view.dev)
                raw3270_activate_view(&cp->view);

        wrq = xchg(&cp->write, 0);
        if (!wrq) {
                con3270_set_timer(cp, 1);
                return;
        }

        spin_lock_irqsave(&cp->view.lock, flags);
        updated = 0;
        if (cp->update_flags & CON_UPDATE_ALL) {
                con3270_rebuild_update(cp);
                con3270_update_status(cp);
                cp->update_flags = CON_UPDATE_ERASE | CON_UPDATE_LIST |
                        CON_UPDATE_STATUS;
        }
        if (cp->update_flags & CON_UPDATE_ERASE) {
                /* Use erase write alternate to initialize display. */
                raw3270_request_set_cmd(wrq, TC_EWRITEA);
                updated |= CON_UPDATE_ERASE;
        } else
                raw3270_request_set_cmd(wrq, TC_WRITE);

        wcc = TW_NONE;
        raw3270_request_add_data(wrq, &wcc, 1);

        /*
         * Update status line.
         */
        if (cp->update_flags & CON_UPDATE_STATUS)
                if (raw3270_request_add_data(wrq, cp->status->string,
                                             cp->status->len) == 0)
                        updated |= CON_UPDATE_STATUS;

        if (cp->update_flags & CON_UPDATE_LIST) {
                prolog[0] = TO_SBA;
                prolog[3] = TO_SA;
                prolog[4] = TAT_COLOR;
                prolog[5] = TAC_TURQ;
                raw3270_buffer_address(cp->view.dev, prolog + 1,
                                       cp->view.cols * cp->line_nr);
                raw3270_request_add_data(wrq, prolog, 6);
                /* Write strings in the update list to the screen. */
                list_for_each_entry_safe(s, n, &cp->update, update) {
                        if (s != cp->cline)
                                con3270_update_string(cp, s, cp->line_nr);
                        if (raw3270_request_add_data(wrq, s->string,
                                                     s->len) != 0)
                                break;
                        list_del_init(&s->update);
                        if (s != cp->cline)
                                cp->line_nr++;
                }
                if (list_empty(&cp->update))
                        updated |= CON_UPDATE_LIST;
        }
        wrq->callback = con3270_write_callback;
        rc = raw3270_start(&cp->view, wrq);
        if (rc == 0) {
                cp->update_flags &= ~updated;
                if (cp->update_flags)
                        con3270_set_timer(cp, 1);
        } else {
                raw3270_request_reset(wrq);
                xchg(&cp->write, wrq);
        }
        spin_unlock_irqrestore(&cp->view.lock, flags);
}

/*
 * Read tasklet.
 */
static void
con3270_read_tasklet(unsigned long data)
{
        static char kreset_data = TW_KR;
        struct raw3270_request *rrq;
        struct con3270 *cp;
        unsigned long flags;
        int nr_up, deactivate;

        rrq = (struct raw3270_request *)data;
        cp = (struct con3270 *) rrq->view;
        spin_lock_irqsave(&cp->view.lock, flags);
        nr_up = cp->nr_up;
        deactivate = 0;
        /* Check aid byte. */
        switch (cp->input->string[0]) {
        case 0x7d:      /* enter: jump to bottom. */
                nr_up = 0;
                break;
        case 0xf3:      /* PF3: deactivate the console view. */
                deactivate = 1;
                break;
        case 0x6d:      /* clear: start from scratch. */
                cp->update_flags = CON_UPDATE_ALL;
                con3270_set_timer(cp, 1);
                break;
        case 0xf7:      /* PF7: do a page up in the console log. */
                nr_up += cp->view.rows - 2;
                if (nr_up + cp->view.rows - 1 > cp->nr_lines) {
                        nr_up = cp->nr_lines - cp->view.rows + 1;
                        if (nr_up < 0)
                                nr_up = 0;
                }
                break;
        case 0xf8:      /* PF8: do a page down in the console log. */
                nr_up -= cp->view.rows - 2;
                if (nr_up < 0)
                        nr_up = 0;
                break;
        }
        if (nr_up != cp->nr_up) {
                cp->nr_up = nr_up;
                con3270_rebuild_update(cp);
                con3270_update_status(cp);
                con3270_set_timer(cp, 1);
        }
        spin_unlock_irqrestore(&cp->view.lock, flags);

        /* Start keyboard reset command. */
        raw3270_request_reset(cp->kreset);
        raw3270_request_set_cmd(cp->kreset, TC_WRITE);
        raw3270_request_add_data(cp->kreset, &kreset_data, 1);
        raw3270_start(&cp->view, cp->kreset);

        if (deactivate)
                raw3270_deactivate_view(&cp->view);

        raw3270_request_reset(rrq);
        xchg(&cp->read, rrq);
        raw3270_put_view(&cp->view);
}

/*
 * Read request completion callback.
 */
static void
con3270_read_callback(struct raw3270_request *rq, void *data)
{
        raw3270_get_view(rq->view);
        /* Schedule tasklet to pass input to tty. */
        tasklet_schedule(&((struct con3270 *) rq->view)->readlet);
}

/*
 * Issue a read request. Called only from interrupt function.
 */
static void
con3270_issue_read(struct con3270 *cp)
{
        struct raw3270_request *rrq;
        int rc;

        rrq = xchg(&cp->read, 0);
        if (!rrq)
                /* Read already scheduled. */
                return;
        rrq->callback = con3270_read_callback;
        rrq->callback_data = cp;
        raw3270_request_set_cmd(rrq, TC_READMOD);
        raw3270_request_set_data(rrq, cp->input->string, cp->input->len);
        /* Issue the read modified request. */
        rc = raw3270_start_irq(&cp->view, rrq);
        if (rc)
                raw3270_request_reset(rrq);
}

/*
 * Switch to the console view.
 */
static int
con3270_activate(struct raw3270_view *view)
{
        struct con3270 *cp;

        cp = (struct con3270 *) view;
        cp->update_flags = CON_UPDATE_ALL;
        con3270_set_timer(cp, 1);
        return 0;
}

static void
con3270_deactivate(struct raw3270_view *view)
{
        struct con3270 *cp;

        cp = (struct con3270 *) view;
        del_timer(&cp->timer);
}

static void
con3270_irq(struct con3270 *cp, struct raw3270_request *rq, struct irb *irb)
{
        /* Handle ATTN. Schedule tasklet to read aid. */
        if (irb->scsw.cmd.dstat & DEV_STAT_ATTENTION)
                con3270_issue_read(cp);

        if (rq) {
                if (irb->scsw.cmd.dstat & DEV_STAT_UNIT_CHECK)
                        rq->rc = -EIO;
                else
                        /* Normal end. Copy residual count. */
                        rq->rescnt = irb->scsw.cmd.count;
        } else if (irb->scsw.cmd.dstat & DEV_STAT_DEV_END) {
                /* Interrupt without an outstanding request -> update all */
                cp->update_flags = CON_UPDATE_ALL;
                con3270_set_timer(cp, 1);
        }
}

/* Console view to a 3270 device. */
static struct raw3270_fn con3270_fn = {
        .activate = con3270_activate,
        .deactivate = con3270_deactivate,
        .intv = (void *) con3270_irq
};

static inline void
con3270_cline_add(struct con3270 *cp)
{
        if (!list_empty(&cp->cline->list))
                /* Already added. */
                return;
        list_add_tail(&cp->cline->list, &cp->lines);
        cp->nr_lines++;
        con3270_rebuild_update(cp);
}

static inline void
con3270_cline_insert(struct con3270 *cp, unsigned char c)
{
        cp->cline->string[cp->cline->len++] = 
                cp->view.ascebc[(c < ' ') ? ' ' : c];
        if (list_empty(&cp->cline->update)) {
                list_add_tail(&cp->cline->update, &cp->update);
                cp->update_flags |= CON_UPDATE_LIST;
        }
}

static inline void
con3270_cline_end(struct con3270 *cp)
{
        struct string *s;
        unsigned int size;

        /* Copy cline. */
        size = (cp->cline->len < cp->view.cols - 5) ?
                cp->cline->len + 4 : cp->view.cols;
        s = con3270_alloc_string(cp, size);
        memcpy(s->string, cp->cline->string, cp->cline->len);
        if (cp->cline->len < cp->view.cols - 5) {
                s->string[s->len - 4] = TO_RA;
                s->string[s->len - 1] = 0;
        } else {
                while (--size >= cp->cline->len)
                        s->string[size] = cp->view.ascebc[' '];
        }
        /* Replace cline with allocated line s and reset cline. */
        list_add(&s->list, &cp->cline->list);
        list_del_init(&cp->cline->list);
        if (!list_empty(&cp->cline->update)) {
                list_add(&s->update, &cp->cline->update);
                list_del_init(&cp->cline->update);
        }
        cp->cline->len = 0;
}

/*
 * Write a string to the 3270 console
 */
static void
con3270_write(struct console *co, const char *str, unsigned int count)
{
        struct con3270 *cp;
        unsigned long flags;
        unsigned char c;

        cp = condev;
        spin_lock_irqsave(&cp->view.lock, flags);
        while (count-- > 0) {
                c = *str++;
                if (cp->cline->len == 0)
                        con3270_cline_add(cp);
                if (c != '\n')
                        con3270_cline_insert(cp, c);
                if (c == '\n' || cp->cline->len >= cp->view.cols)
                        con3270_cline_end(cp);
        }
        /* Setup timer to output current console buffer after 1/10 second */
        cp->nr_up = 0;
        if (cp->view.dev && !timer_pending(&cp->timer))
                con3270_set_timer(cp, HZ/10);
        spin_unlock_irqrestore(&cp->view.lock,flags);
}

static struct tty_driver *
con3270_device(struct console *c, int *index)
{
        *index = c->index;
        return tty3270_driver;
}

/*
 * Wait for end of write request.
 */
static void
con3270_wait_write(struct con3270 *cp)
{
        while (!cp->write) {
                raw3270_wait_cons_dev(cp->view.dev);
                barrier();
        }
}

/*
 * The below function is called as a panic/reboot notifier before the
 * system enters a disabled, endless loop.
 *
 * Notice we must use the spin_trylock() alternative, to prevent lockups
 * in atomic context (panic routine runs with secondary CPUs, local IRQs
 * and preemption disabled).
 */
static int con3270_notify(struct notifier_block *self,
                          unsigned long event, void *data)
{
        struct con3270 *cp;
        unsigned long flags;

        cp = condev;
        if (!cp->view.dev)
                return NOTIFY_DONE;
        if (!raw3270_view_lock_unavailable(&cp->view))
                raw3270_activate_view(&cp->view);
        if (!spin_trylock_irqsave(&cp->view.lock, flags))
                return NOTIFY_DONE;
        con3270_wait_write(cp);
        cp->nr_up = 0;
        con3270_rebuild_update(cp);
        con3270_update_status(cp);
        while (cp->update_flags != 0) {
                spin_unlock_irqrestore(&cp->view.lock, flags);
                con3270_update(&cp->timer);
                spin_lock_irqsave(&cp->view.lock, flags);
                con3270_wait_write(cp);
        }
        spin_unlock_irqrestore(&cp->view.lock, flags);

        return NOTIFY_DONE;
}

static struct notifier_block on_panic_nb = {
        .notifier_call = con3270_notify,
        .priority = INT_MIN + 1, /* run the callback late */
};

static struct notifier_block on_reboot_nb = {
        .notifier_call = con3270_notify,
        .priority = INT_MIN + 1, /* run the callback late */
};

/*
 *  The console structure for the 3270 console
 */
static struct console con3270 = {
        .name    = "tty3270",
        .write   = con3270_write,
        .device  = con3270_device,
        .flags   = CON_PRINTBUFFER,
};

/*
 * 3270 console initialization code called from console_init().
 */
static int __init
con3270_init(void)
{
        struct raw3270 *rp;
        void *cbuf;
        int i;

        /* Check if 3270 is to be the console */
        if (!CONSOLE_IS_3270)
                return -ENODEV;

        /* Set the console mode for VM */
        if (MACHINE_IS_VM) {
                cpcmd("TERM CONMODE 3270", NULL, 0, NULL);
                cpcmd("TERM AUTOCR OFF", NULL, 0, NULL);
        }

        rp = raw3270_setup_console();
        if (IS_ERR(rp))
                return PTR_ERR(rp);

        condev = kzalloc(sizeof(struct con3270), GFP_KERNEL | GFP_DMA);
        if (!condev)
                return -ENOMEM;
        condev->view.dev = rp;

        condev->read = raw3270_request_alloc(0);
        condev->read->callback = con3270_read_callback;
        condev->read->callback_data = condev;
        condev->write = raw3270_request_alloc(CON3270_OUTPUT_BUFFER_SIZE);
        condev->kreset = raw3270_request_alloc(1);

        INIT_LIST_HEAD(&condev->lines);
        INIT_LIST_HEAD(&condev->update);
        timer_setup(&condev->timer, con3270_update, 0);
        tasklet_init(&condev->readlet, con3270_read_tasklet,
                     (unsigned long) condev->read);

        raw3270_add_view(&condev->view, &con3270_fn, 1, RAW3270_VIEW_LOCK_IRQ);

        INIT_LIST_HEAD(&condev->freemem);
        for (i = 0; i < CON3270_STRING_PAGES; i++) {
                cbuf = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
                add_string_memory(&condev->freemem, cbuf, PAGE_SIZE);
        }
        condev->cline = alloc_string(&condev->freemem, condev->view.cols);
        condev->cline->len = 0;
        con3270_create_status(condev);
        condev->input = alloc_string(&condev->freemem, 80);
        atomic_notifier_chain_register(&panic_notifier_list, &on_panic_nb);
        register_reboot_notifier(&on_reboot_nb);
        register_console(&con3270);
        return 0;
}

console_initcall(con3270_init);